Media Types

Get MIME type from string

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The following example shows how to parse a MIME type from a string using the mime crate. FromStrError produces a default MIME type in an unwrap_or clause.

use mime::{Mime, APPLICATION_OCTET_STREAM}; fn main() { let invalid_mime_type = "i n v a l i d"; let default_mime = invalid_mime_type .parse::<Mime>() .unwrap_or(APPLICATION_OCTET_STREAM); println!( "MIME for {:?} used default value {:?}", invalid_mime_type, default_mime ); let valid_mime_type = "TEXT/PLAIN"; let parsed_mime = valid_mime_type .parse::<Mime>() .unwrap_or(APPLICATION_OCTET_STREAM); println!( "MIME for {:?} was parsed as {:?}", valid_mime_type, parsed_mime ); }

Get MIME type from filename

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The following example shows how to return the correct MIME type from a given filename using the mime crate. The program will check for file extensions and match against a known list. The return value is mime:Mime.

use mime::Mime; fn find_mimetype (filename : &String) -> Mime{ let parts : Vec<&str> = filename.split('.').collect(); let res = match parts.last() { Some(v) => match *v { "png" => mime::IMAGE_PNG, "jpg" => mime::IMAGE_JPEG, "json" => mime::APPLICATION_JSON, &_ => mime::TEXT_PLAIN, }, None => mime::TEXT_PLAIN, }; return res; } fn main() { let filenames = vec!("foobar.jpg", "foo.bar", "foobar.png"); for file in filenames { let mime = find_mimetype(&file.to_owned()); println!("MIME for {}: {}", file, mime); } }

Parse the MIME type of a HTTP response

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When receiving a HTTP reponse from reqwest the MIME type or media type may be found in the Content-Type header. reqwest::header::HeaderMap::get retrieves the header as a reqwest::header::HeaderValue, which can be converted to a string. The mime crate can then parse that, yielding a mime::Mime value.

The mime crate also defines some commonly used MIME types.

Note that the reqwest::header module is exported from the http crate.

use error_chain::error_chain; use mime::Mime; use std::str::FromStr; use reqwest::header::CONTENT_TYPE; error_chain! { foreign_links { Reqwest(reqwest::Error); Header(reqwest::header::ToStrError); Mime(mime::FromStrError); } } #[tokio::main] async fn main() -> Result<()> { let response = reqwest::get("https://www.rust-lang.org/logos/rust-logo-32x32.png").await?; let headers = response.headers(); match headers.get(CONTENT_TYPE) { None => { println!("The response does not contain a Content-Type header."); } Some(content_type) => { let content_type = Mime::from_str(content_type.to_str()?)?; let media_type = match (content_type.type_(), content_type.subtype()) { (mime::TEXT, mime::HTML) => "a HTML document", (mime::TEXT, _) => "a text document", (mime::IMAGE, mime::PNG) => "a PNG image", (mime::IMAGE, _) => "an image", _ => "neither text nor image", }; println!("The reponse contains {}.", media_type); } }; Ok(()) }